1. Field of the Invention
The present invention relates to an exposure apparatus that projects the pattern of an original onto a substrate by a projection optical system to expose the substrate, and a method of manufacturing a device using the same.
2. Description of the Related Art
A projection optical system of an exposure apparatus employed to manufacture flat panel displays such as a liquid crystal display includes a reflecting mirror, concave mirror, convex mirror, concave mirror, and reflecting mirror in turn from the object plane to the image plane. The two reflecting mirrors are used to bend the optical axis of the projection optical system. The exposure region of an exposure apparatus for manufacturing flat panel displays is widening to meet demands for, for example, an increase in size of displays and a reduction in manufacturing cost. To widen the exposure region, it is necessary to increase the sizes of optical elements which constitute a projection optical system. As the sizes of optical elements increase, that of a manufacturing apparatus for manufacturing them, in turn, increases.
Conventionally, two bending mirrors built in a projection optical system are often manufactured to have an integrated structure in which their reflecting surfaces form a right angle with each other. Unfortunately, a demand for widening the exposure region has made it difficult to manufacture two bending mirrors having such an integrated structure.
Japanese Patent No. 3445021 discloses a mirror optical system including two separate reflecting mirrors as bending mirrors. However, Japanese Patent No. 3445021 neither discloses nor suggests details of a supporting mechanism which supports the two reflecting mirrors for bending the optical axis.